Overview
The UC3843BD1 is a high-performance current mode PWM (Pulse Width Modulation) controller from STMicroelectronics. It is part of the UC384xB family, which is designed to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. This IC is particularly suited for applications requiring precise frequency control and high current handling capabilities.
Key Specifications
| Parameter | Unit | Min. | Typ. | Max. |
|---|---|---|---|---|
| Supply Voltage (Vi) | V | − | − | 30 |
| Oscillator Frequency (fOSC) | kHz | 48 | 250 | 275 |
| Output Current (IO) | A | −1 | − | 1 |
| Output Low Level (VOL) | V | 0.1 | 0.4 | 0.4 |
| Output High Level (VOH) | V | 12 | 13.5 | 13.5 |
| Under-Voltage Lockout (UVLO) Start Threshold | V | 7.8 | 8.4 | 9.0 |
| Maximum Duty Cycle | % | 94 | 96 | 100 |
| Start-up Current (Ist) | mA | 0.3 | 0.5 | 0.5 |
| Operating Supply Current (Ii) | mA | 12 | 17 | 17 |
Key Features
- Trimmed Oscillator: Provides precise frequency control up to 500 kHz.
- Current Mode Operation: Supports current mode control with cycle-by-cycle current limiting.
- Internally Trimmed Reference: Features an internally trimmed reference with under-voltage lockout and hysteresis.
- High Current Totem Pole Output: Capable of sourcing or sinking high peak currents, suitable for driving N-Channel MOSFETs.
- Automatic Feed Forward Compensation: Ensures stable operation.
- Low Start-up and Operating Current: Start-up current less than 0.5 mA and low operating current.
- Under-Voltage Lockout with Hysteresis: Prevents the IC from operating below a specified voltage threshold.
- Soft-Start Capability: Can be implemented using external components to reduce inrush current during startup.
Applications
- Off-line Power Supplies: Suitable for designing off-line power supplies with high efficiency and reliability.
- DC to DC Converters: Ideal for fixed frequency current mode DC to DC conversion applications.
- Switch Mode Power Supplies: Used in various switch mode power supply designs requiring precise control and high current handling.
- Industrial Power Systems: Can be used in industrial power systems where robust and reliable power control is essential.
Q & A
- What is the UC3843BD1 used for?
The UC3843BD1 is used to implement off-line or DC to DC fixed frequency current mode control schemes in power supply applications.
- What is the maximum oscillator frequency of the UC3843BD1?
The maximum oscillator frequency is up to 500 kHz.
- What is the under-voltage lockout (UVLO) start threshold for the UC3843BD1?
The UVLO start threshold is between 7.8 V and 9.0 V.
- What is the maximum duty cycle of the UC3843BD1?
The maximum duty cycle is up to 100%.
- How much current can the output stage of the UC3843BD1 handle?
The output stage can source or sink peak currents up to 1 A.
- What is the typical start-up current of the UC3843BD1?
The typical start-up current is less than 0.5 mA.
- Can the UC3843BD1 be used in high-temperature environments?
Yes, it can operate in junction temperatures ranging from -40°C to 150°C.
- How is the oscillator frequency programmed in the UC3843BD1?
The oscillator frequency is programmed by connecting a resistor (RT) to Vref and a capacitor (CT) to ground.
- What type of output stage does the UC3843BD1 have?
The UC3843BD1 has a high current totem pole output stage.
- Is the UC3843BD1 suitable for driving N-Channel MOSFETs?
Yes, it is designed to drive N-Channel MOSFETs.
